In a commonly-used form, such boxes are made up of at least two portions, one of which is, for example, a hollow body which receives at least one cable, optionally in through manner, and which houses equipment. A second portion, e.g. constituting a lid, is positioned over an access opening provided in the first portion so as to close off said opening in sealed manner. It is known that a gasket of linear appearance, optionally an endless gasket, e.g. a gasket made of an elastomer material, can be placed in the zone in which the second portion comes into abutment against the first portion, at the edge of the opening. In a conventional form, a peripheral groove for receiving a linear gasket extends around the edge of the opening of the first portion, a complementary rib provided on the second portion coming into position facing the groove so as to compress the gasket when the second portion is put in place. The second portion compressing the gasket guarantees that the box is sealed at the zone of the first portion that surrounds the opening. Naturally, the positions of the groove and of the rib may be inverted, and grooves and ribs may be combined as a function of particular needs for the purpose of obtaining good sealing.
A cable penetrating into a sealed box, as described above, involves implementing special means if the sealing of the box is to be preserved. It is known that stuffing-type means can be used in an orifice through which a cable passes and which is provided in a wall of one portion of the box, e.g. in the form of a circular hole. Unfortunately, that involves threading the cable through the orifice, which is sometimes impractical, in particular when the cable passes through the box. To avoid that drawback, it is known that provision can be made to pass a cable through a slot which opens out at the edge of an opening.
Document EP-A-695 600 discloses a cable access provided in a gasket zone between two portions that are recessed in complementary manner for this purpose. The sealing means relating to that access essentially comprise a cable clamp surrounding the cable, a gasket of cylindrical appearance through which the cable passes, and a gasket-pressing member, of the washer type. The washer is placed on the other side of the gasket from the cable clamp, and it presses the gasket against a complementary wall of a neck provided at the facing recesses in the two box portions when those portions are suitably assembled together, and when the presser member exerts pressure parallel to the axis of the cable from the cable clamp.
The means proposed in that document suffer from the drawback of requiring a relatively large number of separate parts, and of involving a relatively difficult fitting stage. In addition, the required sealing can be difficult to obtain, in particular when fins are present on the cylindrical gasket, and in particular when it is necessary to fit the sealing means on a box already installed in situ.